Obesity is Linked to Less Diversity of Bacteria in the Gut Microbiome
The gut microbiome can be considered an equivalent of a fingerprint of the gut in the sense that everyone has a unique community of bacteria growing inside them living symbiotically and aiding in digestion. Antibiotics when taken as a cure can also lead to dramatic loss in the diversity of the gut microbiome. Individuals who still have an appendix can restore the diversity of their gut much faster than those who don’t because the organ can function to protect bacterial communities within the gut. A recent study from the Center for Genome Sciences at the Washington Univeristy School of Medicine released a paper detailing significant differences of the diversity and types of bacteria found in the gut microbiome of the obese and lean twins. The experimental methods involved analyzing the stool samples from a small group of unrelated adults and sequencing the 16S rRNA genes to identify the bacteria. The results revealed that twins had a similar gut microbiome community, yet still showed variance in fraternal and identical twins. Lean individuals were associated with higher diversity among bacterial communities compared to obese individuals.

Obesity is Linked to Less Diversity of Bacteria in the Gut Microbiome

The color in this image reflect the different types of bacteria and their amount within the microbiome of the gut.

The figure to the left is taken directly from the paper and the relative abundance of bacterial species from different phylogenetic groups. The lean individuals on the left are found to have a much greater proportion of Bacteroidetes compared to abundance of Firmicutes. The data shows for the obese individuals a greater amount of the Firmicutes with varying amounts of Actinobacteria, but much less Bacteroidetes than the lean individuals. Another study from the University of Pennsylvania appeared in science comparing the eating habits of people from around the world. Two diet types were compared: those who ate primarily a Western diet of high fat and low fiber and those who ate a low fat high fiber diet. Similar experimental methods were used testing fecal matter for 16s rRNA sequencing to identify different strains of bacteria. This results from this papers showed the people from the study clustered into two groups with similar gut microbiome communities. The Western diet is well known to be linked to obesity and cardiovascular problems, but now the research of the bacterial communities in the gut are linked to diet and obesity.  The researchers concluded long term diets of a high protein animal fat diet led to a higher levels of genus Bacteroides species while high carbohidydrate diets led to prevalence of genus Prevotella. What these papers concluded is the diet is responsible for the development of two enterotypes of bacteria in the gut, but the bacterial communities will remain stable unless diet is changed over a long term.

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